Experimental and numerical investigations of the seismic response of a rock–soil mixture deposit slope

Abstract

Inertial instability-induced slope failure is one of the most destructive seismic hazards encountered in China. Depositional slopes are widely distributed across the south-western part of China. To study the seismic performance of rock–soil mixture deposit (RSMD) slopes in detail, physical and mechanical tests of air-dried RSMD, and a 1:50 geometric scale, generalised RSMD slope centrifugal shaking table modelling tests were conducted. The acceleration response, slope deformation, and instability mode of the air-dried RSMD slope under the continuous action of four earthquakes with different intensities are analysed. Besides, the dynamic finite-difference numerical simulations were performed with FLAC to simulate the centrifuge model test. The numerical simulation results were compared with the test results in terms of the horizontal acceleration response, time history of crest settlements, and the slope failure characteristics. The results show that the horizontal peak ground acceleration (PGA) amplification factors of the RSMD slope reflect typical elevation, and surface, amplification effects. In addition, the spectral distribution of the seismic wave has changed significantly with propagation along the slope elevation. The energy of input seismic wave in a frequency range close to the natural frequency of an RSMD slope is significantly amplified. During the test, it was observed that the failure of an air-dried RSMD slope occurred when the PGA reached 0.216 g, and the settlement at the crest of the slope was obvious. The failure mode was dominated by shallow collapse.